Apparatus for transmitting broadcast signals, apparatus for receiving broadcast signals, method for transmitting broadcast signals and method for receiving broadcast signals

ABSTRACT

A method and an apparatus for transmitting broadcast signals thereof are disclosed. The apparatus for transmitting broadcast signals comprises an input formatter to format at least one input stream to output DP (Data Pipe) data corresponding to each of a plurality of DPs, wherein the each of a plurality of DPs carries at least one service or at least one service component, an encoder to encode the DP data, a mapper to map the encoded DP data onto constellations, a time interleaver to time interleave the mapped DP data, a frame builder to build at least one signal frame including the time interleaved DP data, a modulator to modulate data in the built at least one signal frame by an OFDM (Orthogonal Frequency Division Multiplex) scheme and a transmitter to transmit the broadcast signals having the modulated data.

This application is a Continuation Application of U.S. patentapplication Ser. No. 14/278,431, filed on May 15, 2014, and claims thebenefit of U.S. Provisional Application No. 61/823,886 filed on May 15,2013, 61/823,891 filed on May 15, 2013, and 61/883,959 filed Sep. 27,2013 in the US, the entire contents of which is hereby incorporated byreference in their entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an apparatus for transmitting broadcastsignals, an apparatus for receiving broadcast signals and methods fortransmitting and receiving broadcast signals.

Discussion of the Related Art

As analog broadcast signal transmission comes to an end, varioustechnologies for transmitting/receiving digital broadcast signals arebeing developed. A digital broadcast signal may include a larger amountof video/audio data than an analog broadcast signal and further includevarious types of additional data in addition to the video/audio data.

That is, a digital broadcast system can provide HD (high definition)images, multi-channel audio and various additional services. However,data transmission efficiency for transmission of large amounts of data,robustness of transmission/reception networks and network flexibility inconsideration of mobile reception equipment need to be improved fordigital broadcast.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an apparatus fortransmitting broadcast signals and an apparatus for receiving broadcastsignals for future broadcast services and methods for transmitting andreceiving broadcast signals for future broadcast services.

An object of the present invention is to provide an apparatus and methodfor transmitting broadcast signals to multiplex data of a broadcasttransmission/reception system providing two or more different broadcastservices in a time domain and transmit the multiplexed data through thesame RF signal bandwidth and an apparatus and method for receivingbroadcast signals corresponding thereto.

Another object of the present invention is to provide an apparatus fortransmitting broadcast signals, an apparatus for receiving broadcastsignals and methods for transmitting and receiving broadcast signals toclassify data corresponding to services by components, transmit datacorresponding to each component as a data pipe, receive and process thedata

Still another object of the present invention is to provide an apparatusfor transmitting broadcast signals, an apparatus for receiving broadcastsignals and methods for transmitting and receiving broadcast signals tosignal signaling information necessary to provide broadcast signals.

Technical Solution

To achieve the object and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, amethod for transmitting broadcast signals comprises formatting at leastone input stream to output DP (Data Pipe) data corresponding to each ofa plurality of DPs, wherein the each of a plurality of DPs carries atleast one service or at least one service component, wherein theformatting further includes splitting the at least one input stream intothe DP data having data packets and compressing a header in the each ofthe data packets according to a header compression mode, encoding the DPdata, mapping the encoded DP data onto constellations, time interleavingthe mapped DP data, building at least one signal frame including thetime interleaved DP data, modulating data in the built at least onesignal frame by an OFDM (Orthogonal Frequency Division Multiplex) schemeand transmitting the broadcast signals having the modulated data.

Advantageous Effects

The present invention can process data according to servicecharacteristics to control QoS for each service or service component,thereby providing various broadcast services.

The present invention can achieve transmission flexibility bytransmitting various broadcast services through the same RF signalbandwidth.

The present invention can improve data transmission efficiency andincrease robustness of transmission/reception of broadcast signals usinga MIMO system.

According to the present invention, it is possible to provide broadcastsignal transmission and reception methods and apparatus capable ofreceiving digital broadcast signals without error even with mobilereception equipment or in an indoor environment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a structure of an apparatus for transmittingbroadcast signals for future broadcast services according to anembodiment of the present invention.

FIG. 2 illustrates an input formatting module according to an embodimentof the present invention.

FIG. 3 illustrates an input formatting module according to anotherembodiment of the present invention.

FIG. 4 illustrates an input formatting module according to anotherembodiment of the present invention.

FIG. 5 illustrates a coding & modulation module according to anembodiment of the present invention.

FIG. 6 illustrates a frame structure module according to an embodimentof the present invention.

FIG. 7 illustrates a waveform generation module according to anembodiment of the present invention.

FIG. 8 illustrates a structure of an apparatus for receiving broadcastsignals for future broadcast services according to an embodiment of thepresent invention.

FIG. 9 illustrates a synchronization & demodulation module according toan embodiment of the present invention.

FIG. 10 illustrates a frame parsing module according to an embodiment ofthe present invention.

FIG. 11 illustrates a demapping & decoding module according to anembodiment of the present invention.

FIG. 12 illustrates an output processor according to an embodiment ofthe present invention.

FIG. 13 illustrates an output processor according to another embodimentof the present invention.

FIG. 14 illustrates a coding & modulation module according to anotherembodiment of the present invention.

FIG. 15 illustrates a demapping & decoding module according to anotherembodiment of the present invention.

FIG. 16 is a view showing a header compression block according to anembodiment of the present invention.

FIG. 17 is a view showing a header de-compression block according to anembodiment of the present invention.

FIG. 18 is a flowchart showing a header compression process according toan embodiment of the present invention.

FIG. 19 is a flowchart showing a header de-compression process accordingto an embodiment of the present invention.

FIG. 20 is a view showing a relationship between a TS header compressedaccording to a Sync byte deletion mode according to an embodiment of thepresent invention and an original TS header.

FIG. 21 is a view showing a relationship between a TS header compressedaccording to a PID compression mode according to an embodiment of thepresent invention and an original TS header.

FIG. 22 is a table showing a PID-sub according to an embodiment of thepresent invention.

FIG. 23 is a view showing a PID compression process according to anembodiment of the present invention.

FIG. 24 is a view showing a relationship between a TS header compressedaccording to a PID deletion mode according to an embodiment of thepresent invention and an original TS header.

FIG. 25 is a view showing a PMT according to an embodiment of thepresent invention.

FIG. 26 is a view showing a relationship between a TS header compressedaccording to a PID compression mode according to another embodiment ofthe present invention and an original TS header.

FIG. 27 is a view showing a table indicating a PID-sub according toanother embodiment of the present invention and a mapping table forcontinuity counter compression.

FIG. 28 is a view showing a PID compression process according to anotherembodiment of the present invention.

FIG. 29 is a view showing a null packet deletion block according toanother embodiment of the present invention.

FIG. 30 is a view showing a null packet insertion block according toanother embodiment of the present invention.

FIG. 31 is a view showing a DNP extension method according to anembodiment of the present invention.

FIG. 32 is a view showing a DNP offset according to an embodiment of thepresent invention.

FIG. 33 is a flowchart illustrating a method for transmitting broadcastsignals according to an embodiment of the present invention.

FIG. 34 is a flowchart illustrating a method for receiving broadcastsignals according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The detailed description, which will be given below withreference to the accompanying drawings, is intended to explain exemplaryembodiments of the present invention, rather than to show the onlyembodiments that can be implemented according to the present invention.The following detailed description includes specific details in order toprovide a thorough understanding of the present invention. However, itwill be apparent to those skilled in the art that the present inventionmay be practiced without such specific details.

Although most terms used in the present invention have been selectedfrom general ones widely used in the art, some terms have beenarbitrarily selected by the applicant and their meanings are explainedin detail in the following description as needed. Thus, the presentinvention should be understood based upon the intended meanings of theterms rather than their simple names or meanings.

The present invention provides apparatuses and methods for transmittingand receiving broadcast signals for future broadcast services. Futurebroadcast services according to an embodiment of the present inventioninclude a terrestrial broadcast service, a mobile broadcast service, aUHDTV service, etc. The present invention may process broadcast signalsfor the future broadcast services through non-MIMO (Multiple InputMultiple Output) or MIMO according to one embodiment. A non-MIMO schemeaccording to an embodiment of the present invention may include a MISO(Multiple Input Single Output) scheme, a SISO (Single Input SingleOutput) scheme, etc.

While MISO or MIMO uses two antennas in the following for convenience ofdescription, the present invention is applicable to systems using two ormore antennas.

FIG. 1 illustrates a structure of an apparatus for transmittingbroadcast signals for future broadcast services according to anembodiment of the present invention.

The apparatus for transmitting broadcast signals for future broadcastservices according to an embodiment of the present invention can includean input formatting module 1000, a coding & modulation module 1100, aframe structure module 1200, a waveform generation module 1300 and asignaling generation module 1400. A description will be given of theoperation of each module of the apparatus for transmitting broadcastsignals.

Referring to FIG. 1, the apparatus for transmitting broadcast signalsfor future broadcast services according to an embodiment of the presentinvention can receive MPEG-TSs, IP streams (v4/v6) and generic streams(GSs) as an input signal. In addition, the apparatus for transmittingbroadcast signals can receive management information about theconfiguration of each stream constituting the input signal and generatea final physical layer signal with reference to the received managementinformation.

The input formatting module 1000 according to an embodiment of thepresent invention can classify the input streams on the basis of astandard for coding and modulation or services or service components andoutput the input streams as a plurality of logical data pipes (or datapipes or DP data). The data pipe is a logical channel in the physicallayer that carries service data or related metadata, which may carry oneor multiple service(s) or service component(s). In addition, datatransmitted through each data pipe may be called DP data.

In addition, the input formatting module 1000 according to an embodimentof the present invention can divide each data pipe into blocks necessaryto perform coding and modulation and carry out processes necessary toincrease transmission efficiency or to perform scheduling. Details ofoperations of the input formatting module 1000 will be described later.

The coding & modulation module 1100 according to an embodiment of thepresent invention can perform forward error correction (FEC) encoding oneach data pipe received from the input formatting module 1000 such thatan apparatus for receiving broadcast signals can correct an error thatmay be generated on a transmission channel. In addition, the coding &modulation module 1100 according to an embodiment of the presentinvention can convert FEC output bit data to symbol data and interleavethe symbol data to correct burst error caused by a channel. As shown inFIG. 1, the coding & modulation module 1100 according to an embodimentof the present invention can divide the processed data such that thedivided data can be output through data paths for respective antennaoutputs in order to transmit the data through two or more Tx antennas.

The frame structure module 1200 according to an embodiment of thepresent invention can map the data output from the coding & modulationmodule 1100 to signal frames. The frame structure module 1200 accordingto an embodiment of the present invention can perform mapping usingscheduling information output from the input formatting module 1000 andinterleave data in the signal frames in order to obtain additionaldiversity gain.

The waveform generation module 1300 according to an embodiment of thepresent invention can convert the signal frames output from the framestructure module 1200 into a signal for transmission. In this case, thewaveform generation module 1300 according to an embodiment of thepresent invention can insert a preamble signal (or preamble) into thesignal for detection of the transmission apparatus and insert areference signal for estimating a transmission channel to compensate fordistortion into the signal. In addition, the waveform generation module1300 according to an embodiment of the present invention can provide aguard interval and insert a specific sequence into the same in order tooffset the influence of channel delay spread due to multi-pathreception. Additionally, the waveform generation module 1300 accordingto an embodiment of the present invention can perform a procedurenecessary for efficient transmission in consideration of signalcharacteristics such as a peak-to-average power ratio of the outputsignal.

The signaling generation module 1400 according to an embodiment of thepresent invention generates final physical layer signaling informationusing the input management information and information generated by theinput formatting module 1000, coding & modulation module 1100 and framestructure module 1200. Accordingly, a reception apparatus according toan embodiment of the present invention can decode a received signal bydecoding the signaling information.

As described above, the apparatus for transmitting broadcast signals forfuture broadcast services according to one embodiment of the presentinvention can provide terrestrial broadcast service, mobile broadcastservice, UHDTV service, etc. Accordingly, the apparatus for transmittingbroadcast signals for future broadcast services according to oneembodiment of the present invention can multiplex signals for differentservices in the time domain and transmit the same.

FIGS. 2, 3 and 4 illustrate the input formatting module 1000 accordingto embodiments of the present invention. A description will be given ofeach figure.

FIG. 2 illustrates an input formatting module according to oneembodiment of the present invention. FIG. 2 shows an input formattingmodule when the input signal is a single input stream.

Referring to FIG. 2, the input formatting module according to oneembodiment of the present invention can include a mode adaptation module2000 and a stream adaptation module 2100.

As shown in FIG. 2, the mode adaptation module 2000 can include an inputinterface block 2010, a CRC-8 encoder block 2020 and a BB headerinsertion block 2030. Description will be given of each block of themode adaptation module 2000.

The input interface block 2010 can divide the single input stream inputthereto into data pieces each having the length of a baseband (BB) frameused for FEC (BCH/LDPC) which will be performed later and output thedata pieces.

The CRC-8 encoder block 2020 can perform CRC encoding on BB frame datato add redundancy data thereto.

The BB header insertion block 2030 can insert, into the BB frame data, aheader including information such as mode adaptation type (TS/GS/IP), auser packet length, a data field length, user packet sync byte, startaddress of user packet sync byte in data field, a high efficiency modeindicator, an input stream synchronization field, etc.

As shown in FIG. 2, the stream adaptation module 2100 can include apadding insertion block 2110 and a BB scrambler block 2120. Descriptionwill be given of each block of the stream adaptation module 2100.

If data received from the mode adaptation module 2000 has a lengthshorter than an input data length necessary for FEC encoding, thepadding insertion block 2110 can insert a padding bit into the data suchthat the data has the input data length and output the data includingthe padding bit.

The BB scrambler block 2120 can randomize the input bit stream byperforming an XOR operation on the input bit stream and a pseudo randombinary sequence (PRBS).

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

As shown in FIG. 2, the input formatting module can finally output datapipes to the coding & modulation module.

FIG. 3 illustrates an input formatting module according to anotherembodiment of the present invention. FIG. 3 shows a mode adaptationmodule 3000 of the input formatting module when the input signalcorresponds to multiple input streams.

The mode adaptation module 3000 of the input formatting module forprocessing the multiple input streams can independently process themultiple input streams.

Referring to FIG. 3, the mode adaptation module 3000 for respectivelyprocessing the multiple input streams can include input interfaceblocks, input stream synchronizer blocks 3100, compensating delay blocks3200, null packet deletion blocks 3300, CRC-8 encoder blocks and BBheader insertion blocks. Description will be given of each block of themode adaptation module 3000.

Operations of the input interface block, CRC-8 encoder block and BBheader insertion block correspond to those of the input interface block,CRC-8 encoder block and BB header insertion block described withreference to FIG. 2 and thus description thereof is omitted.

The input stream synchronizer block 3100 can transmit input stream clockreference (ISCR) information to generate timing information necessaryfor the apparatus for receiving broadcast signals to restore the TSs orGSs.

The compensating delay block 3200 can delay input data and output thedelayed input data such that the apparatus for receiving broadcastsignals can synchronize the input data if a delay is generated betweendata pipes according to processing of data including the timinginformation by the transmission apparatus.

The null packet deletion block 3300 can delete unnecessarily transmittedinput null packets from the input data, insert the number of deletednull packets into the input data based on positions in which the nullpackets are deleted and transmit the input data.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 4 illustrates an input formatting module according to anotherembodiment of the present invention.

Specifically, FIG. 4 illustrates a stream adaptation module of the inputformatting module when the input signal corresponds to multiple inputstreams.

The stream adaptation module of the input formatting module when theinput signal corresponds to multiple input streams can include ascheduler 4000, a 1-frame delay block 4100, an in-band signaling orpadding insertion block 4200, a physical layer signaling generationblock 4300 and a BB scrambler block 4400. Description will be given ofeach block of the stream adaptation module.

The scheduler 4000 can perform scheduling for a MIMO system usingmultiple antennas having dual polarity. In addition, the scheduler 4000can generate parameters for use in signal processing blocks for antennapaths, such as a bit-to-cell demux block, a cell interleaver block, atime interleaver block, etc. included in the coding & modulation moduleillustrated in FIG. 1.

The 1-frame delay block 4100 can delay the input data by onetransmission frame such that scheduling information about the next framecan be transmitted through the current frame for in-band signalinginformation to be inserted into the data pipes.

The in-band signaling or padding insertion block 4200 can insertundelayed physical layer signaling (PLS)-dynamic signaling informationinto the data delayed by one transmission frame. In this case, thein-band signaling or padding insertion block 4200 can insert a paddingbit when a space for padding is present or insert in-band signalinginformation into the padding space. In addition, the scheduler 4000 canoutput physical layer signaling-dynamic signaling information about thecurrent frame separately from in-band signaling information.Accordingly, a cell mapper, which will be described later, can map inputcells according to scheduling information output from the scheduler4000.

The physical layer signaling generation block 4300 can generate physicallayer signaling data which will be transmitted through a preamble symbolof a transmission frame or spread and transmitted through a data symbolother than the in-band signaling information. In this case, the physicallayer signaling data according to an embodiment of the present inventioncan be referred to as signaling information. Furthermore, the physicallayer signaling data according to an embodiment of the present inventioncan be divided into PLS-pre information and PLS-post information. ThePLS-pre information can include parameters necessary to encode thePLS-post information and static PLS signaling data and the PLS-postinformation can include parameters necessary to encode the data pipes.The parameters necessary to encode the data pipes can be classified intostatic PLS signaling data and dynamic PLS signaling data. The static PLSsignaling data is a parameter commonly applicable to all frames includedin a super-frame and can be changed on a super-frame basis. The dynamicPLS signaling data is a parameter differently applicable to respectiveframes included in a super-frame and can be changed on a frame-by-framebasis. Accordingly, the reception apparatus can acquire the PLS-postinformation by decoding the PLS-pre information and decode desired datapipes by decoding the PLS-post information.

The BB scrambler block 4400 can generate a pseudo-random binary sequence(PRBS) and perform an XOR operation on the PRBS and the input bitstreams to decrease the peak-to-average power ratio (PAPR) of the outputsignal of the waveform generation block. As shown in FIG. 4, scramblingof the BB scrambler block 4400 is applicable to both data pipes andphysical layer signaling information.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions according to designer.

As shown in FIG. 4, the stream adaptation module can finally output thedata pipes to the coding & modulation module.

FIG. 5 illustrates a coding & modulation module according to anembodiment of the present invention.

The coding & modulation module shown in FIG. 5 corresponds to anembodiment of the coding & modulation module illustrated in FIG. 1.

As described above, the apparatus for transmitting broadcast signals forfuture broadcast services according to an embodiment of the presentinvention can provide a terrestrial broadcast service, mobile broadcastservice, UHDTV service, etc.

Since QoS (quality of service) depends on characteristics of a serviceprovided by the apparatus for transmitting broadcast signals for futurebroadcast services according to an embodiment of the present invention,data corresponding to respective services needs to be processed throughdifferent schemes. Accordingly, the coding & modulation module accordingto an embodiment of the present invention can independently process datapipes input thereto by independently applying SISO, MISO and MIMOschemes to the data pipes respectively corresponding to data paths.Consequently, the apparatus for transmitting broadcast signals forfuture broadcast services according to an embodiment of the presentinvention can control QoS for each service or service componenttransmitted through each data pipe.

Accordingly, the coding & modulation module according to an embodimentof the present invention can include a first block 5000 for SISO, asecond block 5100 for MISO, a third block 5200 for MIMO and a fourthblock 5300 for processing the PLS-pre/PLS-post information. The coding &modulation module illustrated in FIG. 5 is an exemplary and may includeonly the first block 5000 and the fourth block 5300, the second block5100 and the fourth block 5300 or the third block 5200 and the fourthblock 5300 according to design. That is, the coding & modulation modulecan include blocks for processing data pipes equally or differentlyaccording to design.

A description will be given of each block of the coding & modulationmodule.

The first block 5000 processes an input data pipe according to SISO andcan include an FEC encoder block 5010, a bit interleaver block 5020, abit-to-cell demux block 5030, a constellation mapper block 5040, a cellinterleaver block 5050 and a time interleaver block 5060.

The FEC encoder block 5010 can perform BCH encoding and LDPC encoding onthe input data pipe to add redundancy thereto such that the receptionapparatus can correct an error generated on a transmission channel.

The bit interleaver block 5020 can interleave bit streams of theFEC-encoded data pipe according to an interleaving rule such that thebit streams have robustness against burst error that may be generated onthe transmission channel. Accordingly, when deep fading or erasure isapplied to QAM symbols, errors can be prevented from being generated inconsecutive bits from among all codeword bits since interleaved bits aremapped to the QAM symbols.

The bit-to-cell demux block 5030 can determine the order of input bitstreams such that each bit in an FEC block can be transmitted withappropriate robustness in consideration of both the order of input bitstreams and a constellation mapping rule.

In addition, the bit interleaver block 5020 is located between the FECencoder block 5010 and the constellation mapper block 5040 and canconnect output bits of LDPC encoding performed by the FEC encoder block5010 to bit positions having different reliability values and optimalvalues of the constellation mapper in consideration of LDPC decoding ofthe apparatus for receiving broadcast signals. Accordingly, thebit-to-cell demux block 5030 can be replaced by a block having a similaror equal function.

The constellation mapper block 5040 can map a bit word input thereto toone constellation. In this case, the constellation mapper block 5040 canadditionally perform rotation & Q-delay. That is, the constellationmapper block 5040 can rotate input constellations according to arotation angle, divide the constellations into an in-phase component anda quadrature-phase component and delay only the quadrature-phasecomponent by an arbitrary value. Then, the constellation mapper block5040 can remap the constellations to new constellations using a pairedin-phase component and quadrature-phase component.

In addition, the constellation mapper block 5040 can move constellationpoints on a two-dimensional plane in order to find optimal constellationpoints. Through this process, capacity of the coding & modulation module1100 can be optimized. Furthermore, the constellation mapper block 5040can perform the above-described operation using IQ-balancedconstellation points and rotation. The constellation mapper block 5040can be replaced by a block having a similar or equal function.

The cell interleaver block 5050 can randomly interleave cellscorresponding to one FEC block and output the interleaved cells suchthat cells corresponding to respective FEC blocks can be output indifferent orders.

The time interleaver block 5060 can interleave cells belonging to aplurality of FEC blocks and output the interleaved cells. Accordingly,the cells corresponding to the FEC blocks are dispersed and transmittedin a period corresponding to a time interleaving depth and thusdiversity gain can be obtained.

The second block 5100 processes an input data pipe according to MISO andcan include the FEC encoder block, bit interleaver block, bit-to-celldemux block, constellation mapper block, cell interleaver block and timeinterleaver block in the same manner as the first block 5000. However,the second block 5100 is distinguished from the first block 5000 in thatthe second block 5100 further includes a MISO processing block 5110. Thesecond block 5100 performs the same procedure including the inputoperation to the time interleaver operation as those of the first block5000 and thus description of the corresponding blocks is omitted.

The MISO processing block 5110 can encode input cells according to aMISO encoding matrix providing transmit diversity and outputMISO-processed data through two paths. MISO processing according to oneembodiment of the present invention can include OSTBC (orthogonal spacetime block coding)/OSFBC (orthogonal space frequency block coding,Alamouti coding).

The third block 5200 processes an input data pipe according to MIMO andcan include the FEC encoder block, bit interleaver block, bit-to-celldemux block, constellation mapper block, cell interleaver block and timeinterleaver block in the same manner as the second block 5100, as shownin FIG. 5. However, the data processing procedure of the third block5200 is different from that of the second block 5100 since the thirdblock 5200 includes a MIMO processing block 5220.

That is, in the third block 5200, basic roles of the FEC encoder blockand the bit interleaver block are identical to those of the first andsecond blocks 5000 and 5100 although functions thereof may be differentfrom those of the first and second blocks 5000 and 5100.

The bit-to-cell demux block 5210 can generate as many output bit streamsas input bit streams of MIMO processing and output the output bitstreams through MIMO paths for MIMO processing. In this case, thebit-to-cell demux block 5210 can be designed to optimize the decodingperformance of the reception apparatus in consideration ofcharacteristics of LDPC and MIMO processing.

Basic roles of the constellation mapper block, cell interleaver blockand time interleaver block are identical to those of the first andsecond blocks 5000 and 5100 although functions thereof may be differentfrom those of the first and second blocks 5000 and 5100. As shown inFIG. 5, as many constellation mapper blocks, cell interleaver blocks andtime interleaver blocks as the number of MIMO paths for MIMO processingcan be present. In this case, the constellation mapper blocks, cellinterleaver blocks and time interleaver blocks can operate equally orindependently for data input through the respective paths.

The MIMO processing block 5220 can perform MIMO processing on two inputcells using a MIMO encoding matrix and output the MIMO-processed datathrough two paths. The MIMO encoding matrix according to an embodimentof the present invention can include spatial multiplexing, Golden code,full-rate full diversity code, linear dispersion code, etc.

The fourth block 5300 processes the PLS-pre/PLS-post information and canperform SISO or MISO processing.

The basic roles of the bit interleaver block, bit-to-cell demux block,constellation mapper block, cell interleaver block, time interleaverblock and MISO processing block included in the fourth block 5300correspond to those of the second block 5100 although functions thereofmay be different from those of the second block 5100.

A shortened/punctured FEC encoder block 5310 included in the fourthblock 5300 can process PLS data using an FEC encoding scheme for a PLSpath provided for a case in which the length of input data is shorterthan a length necessary to perform FEC encoding. Specifically, theshortened/punctured FEC encoder block 5310 can perform BCH encoding oninput bit streams, pad 0s corresponding to a desired input bit streamlength necessary for normal LDPC encoding, carry out LDPC encoding andthen remove the padded 0s to puncture parity bits such that an effectivecode rate becomes equal to or lower than the data pipe rate.

The blocks included in the first block 5000 to fourth block 5300 may beomitted or replaced by blocks having similar or identical functionsaccording to design.

As illustrated in FIG. 5, the coding & modulation module can output thedata pipes (or DP data), PLS-pre information and PLS-post informationprocessed for the respective paths to the frame structure module.

FIG. 6 illustrates a frame structure module according to one embodimentof the present invention.

The frame structure module shown in FIG. 6 corresponds to an embodimentof the frame structure module 1200 illustrated in FIG. 1.

The frame structure module according to one embodiment of the presentinvention can include at least one cell-mapper 6000, at least one delaycompensation module 6100 and at least one block interleaver 6200. Thenumber of cell mappers 6000, delay compensation modules 6100 and blockinterleavers 6200 can be changed. A description will be given of eachmodule of the frame structure block.

The cell-mapper 6000 can allocate cells corresponding to SISO-, MISO- orMIMO-processed data pipes output from the coding & modulation module,cells corresponding to common data commonly applicable to the data pipesand cells corresponding to the PLS-pre/PLS-post information to signalframes according to scheduling information. The common data refers tosignaling information commonly applied to all or some data pipes and canbe transmitted through a specific data pipe. The data pipe through whichthe common data is transmitted can be referred to as a common data pipeand can be changed according to design.

When the apparatus for transmitting broadcast signals according to anembodiment of the present invention uses two output antennas andAlamouti coding is used for MISO processing, the cell-mapper 6000 canperform pair-wise cell mapping in order to maintain orthogonalityaccording to Alamouti encoding. That is, the cell-mapper 6000 canprocess two consecutive cells of the input cells as one unit and map theunit to a frame. Accordingly, paired cells in an input pathcorresponding to an output path of each antenna can be allocated toneighboring positions in a transmission frame.

The delay compensation block 6100 can obtain PLS data corresponding tothe current transmission frame by delaying input PLS data cells for thenext transmission frame by one frame. In this case, the PLS datacorresponding to the current frame can be transmitted through a preamblepart in the current signal frame and PLS data corresponding to the nextsignal frame can be transmitted through a preamble part in the currentsignal frame or in-band signaling in each data pipe of the currentsignal frame. This can be changed by the designer.

The block interleaver 6200 can obtain additional diversity gain byinterleaving cells in a transport block corresponding to the unit of asignal frame. In addition, the block interleaver 6200 can performinterleaving by processing two consecutive cells of the input cells asone unit when the above-described pair-wise cell mapping is performed.Accordingly, cells output from the block interleaver 6200 can be twoconsecutive identical cells.

When pair-wise mapping and pair-wise interleaving are performed, atleast one cell mapper and at least one block interleaver can operateequally or independently for data input through the paths.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions according to design.

As illustrated in FIG. 6, the frame structure module can output at leastone signal frame to the waveform generation module.

FIG. 7 illustrates a waveform generation module according to anembodiment of the present invention.

The waveform generation module illustrated in FIG. 7 corresponds to anembodiment of the waveform generation module 1300 described withreference to FIG. 1.

The waveform generation module according to an embodiment of the presentinvention can modulate and transmit as many signal frames as the numberof antennas for receiving and outputting signal frames output from theframe structure module illustrated in FIG. 6.

Specifically, the waveform generation module illustrated in FIG. 7 is anembodiment of a waveform generation module of an apparatus fortransmitting broadcast signals using m Tx antennas and can include mprocessing blocks for modulating and outputting frames corresponding tom paths. The m processing blocks can perform the same processingprocedure. A description will be given of operation of the firstprocessing block 7000 from among the m processing blocks.

The first processing block 7000 can include a reference signal & PAPRreduction block 7100, an inverse waveform transform block 7200, a PAPRreduction in time block 7300, a guard sequence insertion block 7400, apreamble insertion block 7500, a waveform processing block 7600, othersystem insertion block 7700 and a DAC (digital analog converter) block7800.

The reference signal insertion & PAPR reduction block 7100 can insert areference signal into a predetermined position of each signal block andapply a PAPR reduction scheme to reduce a PAPR in the time domain. If abroadcast transmission/reception system according to an embodiment ofthe present invention corresponds to an OFDM system, the referencesignal insertion & PAPR reduction block 7100 can use a method ofreserving some active subcarriers rather than using the same. Inaddition, the reference signal insertion & PAPR reduction block 7100 maynot use the PAPR reduction scheme as an optional feature according tobroadcast transmission/reception system.

The inverse waveform transform block 7200 can transform an input signalin a manner of improving transmission efficiency and flexibility inconsideration of transmission channel characteristics and systemarchitecture. If the broadcast transmission/reception system accordingto an embodiment of the present invention corresponds to an OFDM system,the inverse waveform transform block 7200 can employ a method oftransforming a frequency domain signal into a time domain signal throughinverse FFT operation. If the broadcast transmission/reception systemaccording to an embodiment of the present invention corresponds to asingle carrier system, the inverse waveform transform block 7200 may notbe used in the waveform generation module.

The PAPR reduction in time block 7300 can use a method for reducing PAPRof an input signal in the time domain. If the broadcasttransmission/reception system according to an embodiment of the presentinvention corresponds to an OFDM system, the PAPR reduction in timeblock 7300 may use a method of simply clipping peak amplitude.Furthermore, the PAPR reduction in time block 7300 may not be used inthe broadcast transmission/reception system according to an embodimentof the present invention since it is an optional feature.

The guard sequence insertion block 7400 can provide a guard intervalbetween neighboring signal blocks and insert a specific sequence intothe guard interval as necessary in order to minimize the influence ofdelay spread of a transmission channel. Accordingly, the receptionapparatus can easily perform synchronization or channel estimation. Ifthe broadcast transmission/reception system according to an embodimentof the present invention corresponds to an OFDM system, the guardsequence insertion block 7400 may insert a cyclic prefix into a guardinterval of an OFDM symbol.

The preamble insertion block 7500 can insert a signal of a known type(e.g. the preamble or preamble symbol) agreed upon between thetransmission apparatus and the reception apparatus into a transmissionsignal such that the reception apparatus can rapidly and efficientlydetect a target system signal. If the broadcast transmission/receptionsystem according to an embodiment of the present invention correspondsto an OFDM system, the preamble insertion block 7500 can define a signalframe composed of a plurality of OFDM symbols and insert a preamblesymbol into the beginning of each signal frame. That is, the preamblecarries basic PLS data and is located in the beginning of a signalframe.

The waveform processing block 7600 can perform waveform processing on aninput baseband signal such that the input baseband signal meets channeltransmission characteristics. The waveform processing block 7600 may usea method of performing square-root-raised cosine (SRRC) filtering toobtain a standard for out-of-band emission of a transmission signal. Ifthe broadcast transmission/reception system according to an embodimentof the present invention corresponds to a multi-carrier system, thewaveform processing block 7600 may not be used.

The other system insertion block 7700 can multiplex signals of aplurality of broadcast transmission/reception systems in the time domainsuch that data of two or more different broadcast transmission/receptionsystems providing broadcast services can be simultaneously transmittedin the same RF signal bandwidth. In this case, the two or more differentbroadcast transmission/reception systems refer to systems providingdifferent broadcast services. The different broadcast services may referto a terrestrial broadcast service, mobile broadcast service, etc. Datarelated to respective broadcast services can be transmitted throughdifferent frames.

The DAC block 7800 can convert an input digital signal into an analogsignal and output the analog signal. The signal output from the DACblock 7800 can be transmitted through in output antennas. A Tx antennaaccording to an embodiment of the present invention can have vertical orhorizontal polarity.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions according to design.

FIG. 8 illustrates a structure of an apparatus for receiving broadcastsignals for future broadcast services according to an embodiment of thepresent invention.

The apparatus for receiving broadcast signals for future broadcastservices according to an embodiment of the present invention cancorrespond to the apparatus for transmitting broadcast signals forfuture broadcast services, described with reference to FIG. 1. Theapparatus for receiving broadcast signals for future broadcast servicesaccording to an embodiment of the present invention can include asynchronization & demodulation module 8000, a frame parsing module 8100,a demapping & decoding module 8200, an output processor 8300 and asignaling decoding module 8400. A description will be given of operationof each module of the apparatus for receiving broadcast signals.

The synchronization & demodulation module 8000 can receive input signalsthrough m Rx antennas, perform signal detection and synchronization withrespect to a system corresponding to the apparatus for receivingbroadcast signals and carry out demodulation corresponding to a reverseprocedure of the procedure performed by the apparatus for transmittingbroadcast signals.

The frame parsing module 8100 can parse input signal frames and extractdata through which a service selected by a user is transmitted. If theapparatus for transmitting broadcast signals performs interleaving, theframe parsing module 8100 can carry out deinterleaving corresponding toa reverse procedure of interleaving. In this case, the positions of asignal and data that need to be extracted can be obtained by decodingdata output from the signaling decoding module 8400 to restorescheduling information generated by the apparatus for transmittingbroadcast signals.

The demapping & decoding module 8200 can convert the input signals intobit domain data and then deinterleave the same as necessary. Thedemapping & decoding module 8200 can perform demapping for mappingapplied for transmission efficiency and correct an error generated on atransmission channel through decoding. In this case, the demapping &decoding module 8200 can obtain transmission parameters necessary fordemapping and decoding by decoding the data output from the signalingdecoding module 8400.

The output processor 8300 can perform reverse procedures of variouscompression/signal processing procedures which are applied by theapparatus for transmitting broadcast signals to improve transmissionefficiency. In this case, the output processor 8300 can acquirenecessary control information from data output from the signalingdecoding module 8400. The output of the output processor 8300corresponds to a signal input to the apparatus for transmittingbroadcast signals and may be MPEG-TSs, IP streams (v4 or v6) and genericstreams.

The signaling decoding module 8400 can obtain PLS information from thesignal demodulated by the synchronization & demodulation module 8000. Asdescribed above, the frame parsing module 8100, demapping & decodingmodule 8200 and output processor 8300 can execute functions thereofusing the data output from the signaling decoding module 8400.

FIG. 9 illustrates a synchronization & demodulation module according toan embodiment of the present invention.

The synchronization & demodulation module shown in FIG. 9 corresponds toan embodiment of the synchronization & demodulation module describedwith reference to FIG. 8. The synchronization & demodulation moduleshown in FIG. 9 can perform a reverse operation of the operation of thewaveform generation module illustrated in FIG. 7.

As shown in FIG. 9, the synchronization & demodulation module accordingto an embodiment of the present invention corresponds to asynchronization & demodulation module of an apparatus for receivingbroadcast signals using m Rx antennas and can include m processingblocks for demodulating signals respectively input through m paths. Them processing blocks can perform the same processing procedure. Adescription will be given of operation of the first processing block9000 from among the m processing blocks.

The first processing block 9000 can include a tuner 9100, an ADC block9200, a preamble detector 9300, a guard sequence detector 9400, awaveform transform block 9500, a time/frequency synchronization block9600, a reference signal detector 9700, a channel equalizer 9800 and aninverse waveform transform block 9900.

The tuner 9100 can select a desired frequency band, compensate for themagnitude of a received signal and output the compensated signal to theADC block 9200.

The ADC block 9200 can convert the signal output from the tuner 9100into a digital signal.

The preamble detector 9300 can detect a preamble (or preamble signal orpreamble symbol) in order to check whether or not the digital signal isa signal of the system corresponding to the apparatus for receivingbroadcast signals. In this case, the preamble detector 9300 can decodebasic transmission parameters received through the preamble.

The guard sequence detector 9400 can detect a guard sequence in thedigital signal. The time/frequency synchronization block 9600 canperform time/frequency synchronization using the detected guard sequenceand the channel equalizer 9800 can estimate a channel through areceived/restored sequence using the detected guard sequence.

The waveform transform block 9500 can perform a reverse operation ofinverse waveform transform when the apparatus for transmitting broadcastsignals has performed inverse waveform transform. When the broadcasttransmission/reception system according to one embodiment of the presentinvention is a multi-carrier system, the waveform transform block 9500can perform FFT. Furthermore, when the broadcast transmission/receptionsystem according to an embodiment of the present invention is a singlecarrier system, the waveform transform block 9500 may not be used if areceived time domain signal is processed in the frequency domain orprocessed in the time domain.

The time/frequency synchronization block 9600 can receive output data ofthe preamble detector 9300, guard sequence detector 9400 and referencesignal detector 9700 and perform time synchronization and carrierfrequency synchronization including guard sequence detection and blockwindow positioning on a detected signal. Here, the time/frequencysynchronization block 9600 can feed back the output signal of thewaveform transform block 9500 for frequency synchronization.

The reference signal detector 9700 can detect a received referencesignal. Accordingly, the apparatus for receiving broadcast signalsaccording to an embodiment of the present invention can performsynchronization or channel estimation.

The channel equalizer 9800 can estimate a transmission channel from eachTx antenna to each Rx antenna from the guard sequence or referencesignal and perform channel equalization for received data using theestimated channel.

The inverse waveform transform block 9900 may restore the originalreceived data domain when the waveform transform block 9500 performswaveform transform for efficient synchronization and channelestimation/equalization. If the broadcast transmission/reception systemaccording to an embodiment of the present invention is a single carriersystem, the waveform transform block 9500 can perform FFT in order tocarry out synchronization/channel estimation/equalization in thefrequency domain and the inverse waveform transform block 9900 canperform IFFT on the channel-equalized signal to restore transmitted datasymbols. If the broadcast transmission/reception system according to anembodiment of the present invention is a multi-carrier system, theinverse waveform transform block 9900 may not be used.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions according to design.

FIG. 10 illustrates a frame parsing module according to an embodiment ofthe present invention.

The frame parsing module illustrated in FIG. 10 corresponds to anembodiment of the frame parsing module described with reference to FIG.8. The frame parsing module shown in FIG. 10 can perform a reverseoperation of the operation of the frame structure module illustrated inFIG. 6.

As shown in FIG. 10, the frame parsing module according to an embodimentof the present invention can include at least one block deinterleaver10000 and at least one cell demapper 10100.

The block deinterleaver 10000 can deinterleave data input through datapaths of the m Rx antennas and processed by the synchronization &demodulation module on a signal block basis. In this case, if theapparatus for transmitting broadcast signals performs pair-wiseinterleaving as illustrated in FIG. 8, the block deinterleaver 10000 canprocess two consecutive pieces of data as a pair for each input path.Accordingly, the block interleaver 10000 can output two consecutivepieces of data even when deinterleaving has been performed. Furthermore,the block deinterleaver 10000 can perform a reverse operation of theinterleaving operation performed by the apparatus for transmittingbroadcast signals to output data in the original order.

The cell demapper 10100 can extract cells corresponding to common data,cells corresponding to data pipes and cells corresponding to PLS datafrom received signal frames. The cell demapper 10100 can merge datadistributed and transmitted and output the same as a stream asnecessary. When two consecutive pieces of cell input data are processedas a pair and mapped in the apparatus for transmitting broadcastsignals, as shown in FIG. 6, the cell demapper 10100 can performpair-wise cell demapping for processing two consecutive input cells asone unit as a reverse procedure of the mapping operation of theapparatus for transmitting broadcast signals.

In addition, the cell demapper 10100 can extract PLS signaling datareceived through the current frame as PLS-pre & PLS-post data and outputthe PLS-pre & PLS-post data.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions according to design.

FIG. 11 illustrates a demapping & decoding module according to anembodiment of the present invention.

The demapping & decoding module shown in FIG. 11 corresponds to anembodiment of the demapping & decoding module illustrated in FIG. 8. Thedemapping & decoding module shown in FIG. 11 can perform a reverseoperation of the operation of the coding & modulation module illustratedin FIG. 5.

The coding & modulation module of the apparatus for transmittingbroadcast signals according to an embodiment of the present inventioncan process input data pipes by independently applying SISO, MISO andMIMO thereto for respective paths, as described above. Accordingly, thedemapping & decoding module illustrated in FIG. 11 can include blocksfor processing data output from the frame parsing module according toSISO, MISO and MIMO in response to the apparatus for transmittingbroadcast signals.

As shown in FIG. 11, the demapping & decoding module according to anembodiment of the present invention can include a first block 11000 forSISO, a second block 11100 for MISO, a third block 11200 for MIMO and afourth block 11300 for processing the PLS-pre/PLS-post information. Thedemapping & decoding module shown in FIG. 11 is exemplary and mayinclude only the first block 11000 and the fourth block 11300, only thesecond block 11100 and the fourth block 11300 or only the third block11200 and the fourth block 11300 according to design. That is, thedemapping & decoding module can include blocks for processing data pipesequally or differently according to design.

A description will be given of each block of the demapping & decodingmodule.

The first block 11000 processes an input data pipe according to SISO andcan include a time deinterleaver block 11010, a cell deinterleaver block11020, a constellation demapper block 11030, a cell-to-bit mux block11040, a bit deinterleaver block 11050 and an FEC decoder block 11060.

The time deinterleaver block 11010 can perform a reverse process of theprocess performed by the time interleaver block 5060 illustrated in FIG.5. That is, the time deinterleaver block 11010 can deinterleave inputsymbols interleaved in the time domain into original positions thereof.

The cell deinterleaver block 11020 can perform a reverse process of theprocess performed by the cell interleaver block 5050 illustrated in FIG.5. That is, the cell deinterleaver block 11020 can deinterleavepositions of cells spread in one FEC block into original positionsthereof.

The constellation demapper block 11030 can perform a reverse process ofthe process performed by the constellation mapper block 5040 illustratedin FIG. 5. That is, the constellation demapper block 11030 can demap asymbol domain input signal to bit domain data. In addition, theconstellation demapper block 11030 may perform hard decision and outputdecided bit data. Furthermore, the constellation demapper block 11030may output a log-likelihood ratio (LLR) of each bit, which correspondsto a soft decision value or probability value. If the apparatus fortransmitting broadcast signals applies a rotated constellation in orderto obtain additional diversity gain, the constellation demapper block11030 can perform 2-dimensional LLR demapping corresponding to therotated constellation. Here, the constellation demapper block 11030 cancalculate the LLR such that a delay applied by the apparatus fortransmitting broadcast signals to the I or Q component can becompensated.

The cell-to-bit mux block 11040 can perform a reverse process of theprocess performed by the bit-to-cell demux block 5030 illustrated inFIG. 5. That is, the cell-to-bit mux block 11040 can restore bit datamapped by the bit-to-cell demux block 5030 to the original bit streams.

The bit deinterleaver block 11050 can perform a reverse process of theprocess performed by the bit interleaver 5020 illustrated in FIG. 5.That is, the bit deinterleaver block 11050 can deinterleave the bitstreams output from the cell-to-bit mux block 11040 in the originalorder.

The FEC decoder block 11060 can perform a reverse process of the processperformed by the FEC encoder block 5010 illustrated in FIG. 5. That is,the FEC decoder block 11060 can correct an error generated on atransmission channel by performing LDPC decoding and BCH decoding.

The second block 11100 processes an input data pipe according to MISOand can include the time deinterleaver block, cell deinterleaver block,constellation demapper block, cell-to-bit mux block, bit deinterleaverblock and FEC decoder block in the same manner as the first block 11000,as shown in FIG. 11. However, the second block 11100 is distinguishedfrom the first block 11000 in that the second block 11100 furtherincludes a MISO decoding block 11110. The second block 11100 performsthe same procedure including time deinterleaving operation to outputtingoperation as the first block 11000 and thus description of thecorresponding blocks is omitted.

The MISO decoding block 11110 can perform a reverse operation of theoperation of the MISO processing block 5110 illustrated in FIG. 5. Ifthe broadcast transmission/reception system according to an embodimentof the present invention uses STBC, the MISO decoding block 11110 canperform Alamouti decoding.

The third block 11200 processes an input data pipe according to MIMO andcan include the time deinterleaver block, cell deinterleaver block,constellation demapper block, cell-to-bit mux block, bit deinterleaverblock and FEC decoder block in the same manner as the second block11100, as shown in FIG. 11. However, the third block 11200 isdistinguished from the second block 11100 in that the third block 11200further includes a MIMO decoding block 11210. The basic roles of thetime deinterleaver block, cell deinterleaver block, constellationdemapper block, cell-to-bit mux block and bit deinterleaver blockincluded in the third block 11200 are identical to those of thecorresponding blocks included in the first and second blocks 11000 and11100 although functions thereof may be different from the first andsecond blocks 11000 and 11100.

The MIMO decoding block 11210 can receive output data of the celldeinterleaver for input signals of the m Rx antennas and perform MIMOdecoding as a reverse operation of the operation of the MIMO processingblock 5220 illustrated in FIG. 5. The MIMO decoding block 11210 canperform maximum likelihood decoding to obtain optimal decodingperformance or carry out sphere decoding with reduced complexity.Otherwise, the MIMO decoding block 11210 can achieve improved decodingperformance by performing MMSE detection or carrying out iterativedecoding with MMSE detection.

The fourth block 11300 processes the PLS-pre/PLS-post information andcan perform SISO or MISO decoding. The fourth block 11300 can carry outa reverse process of the process performed by the fourth block 5300described with reference to FIG. 5.

The basic roles of the time deinterleaver block, cell deinterleaverblock, constellation demapper block, cell-to-bit mux block and bitdeinterleaver block included in the fourth block 11300 are identical tothose of the corresponding blocks of the first, second and third blocks11000, 11100 and 11200 although functions thereof may be different fromthe first, second and third blocks 11000, 11100 and 11200.

The shortened/punctured FEC decoder 11310 included in the fourth block11300 can perform a reverse process of the process performed by theshortened/punctured FEC encoder block 5310 described with reference toFIG. 5. That is, the shortened/punctured FEC decoder 11310 can performde-shortening and de-puncturing on data shortened/punctured according toPLS data length and then carry out FEC decoding thereon. In this case,the FEC decoder used for data pipes can also be used for PLS.Accordingly, additional FEC decoder hardware for the PLS only is notneeded and thus system design is simplified and efficient coding isachieved.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions according to design.

The demapping & decoding module according to an embodiment of thepresent invention can output data pipes and PLS information processedfor the respective paths to the output processor, as illustrated in FIG.11.

FIGS. 12 and 13 illustrate output processors according to embodiments ofthe present invention.

FIG. 12 illustrates an output processor according to an embodiment ofthe present invention. The output processor illustrated in FIG. 12corresponds to an embodiment of the output processor illustrated in FIG.8. The output processor illustrated in FIG. 12 receives a single datapipe output from the demapping & decoding module and outputs a singleoutput stream. The output processor can perform a reverse operation ofthe operation of the input formatting module illustrated in FIG. 2.

The output processor shown in FIG. 12 can include a BB scrambler block12000, a padding removal block 12100, a CRC-8 decoder block 12200 and aBB frame processor block 12300.

The BB scrambler block 12000 can descramble an input bit stream bygenerating the same PRBS as that used in the apparatus for transmittingbroadcast signals for the input bit stream and carrying out an XORoperation on the PRBS and the bit stream.

The padding removal block 12100 can remove padding bits inserted by theapparatus for transmitting broadcast signals as necessary.

The CRC-8 decoder block 12200 can check a block error by performing CRCdecoding on the bit stream received from the padding removal block12100.

The BB frame processor block 12300 can decode information transmittedthrough a BB frame header and restore MPEG-TSs, IP streams (v4 or v6) orgeneric streams using the decoded information.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions according to design.

FIG. 13 illustrates an output processor according to another embodimentof the present invention. The output processor shown in FIG. 13corresponds to an embodiment of the output processor illustrated in FIG.8. The output processor shown in FIG. 13 receives multiple data pipesoutput from the demapping & decoding module. Decoding multiple datapipes can include a process of merging common data commonly applicableto a plurality of data pipes and data pipes related thereto and decodingthe same or a process of simultaneously decoding a plurality of servicesor service components (including a scalable video service) by theapparatus for receiving broadcast signals.

The output processor shown in FIG. 13 can include a BB descramblerblock, a padding removal block, a CRC-8 decoder block and a BB frameprocessor block as the output processor illustrated in FIG. 12. Thebasic roles of these blocks correspond to those of the blocks describedwith reference to FIG. 12 although operations thereof may differ fromthose of the blocks illustrated in FIG. 12.

A de-jitter buffer block 13000 included in the output processor shown inFIG. 13 can compensate for a delay, inserted by the apparatus fortransmitting broadcast signals for synchronization of multiple datapipes, according to a restored TTO (time to output) parameter.

A null packet insertion block 13100 can restore a null packet removedfrom a stream with reference to a restored DNP (deleted null packet) andoutput common data.

A TS clock regeneration block 13200 can restore time synchronization ofoutput packets based on ISCR (input stream time reference) information.

A TS recombining block 13300 can recombine the common data and datapipes related thereto, output from the null packet insertion block13100, to restore the original MPEG-TSs, IP streams (v4 or v6) orgeneric streams. The TTO, DNT and ISCR information can be obtainedthrough the BB frame header.

An in-band signaling decoding block 13400 can decode and output in-bandphysical layer signaling information transmitted through a padding bitfield in each FEC frame of a data pipe.

The output processor shown in FIG. 13 can BB-descramble the PLS-preinformation and PLS-post information respectively input through aPLS-pre path and a PLS-post path and decode the descrambled data torestore the original PLS data. The restored PLS data is delivered to asystem controller included in the apparatus for receiving broadcastsignals. The system controller can provide parameters necessary for thesynchronization & demodulation module, frame parsing module, demapping &decoding module and output processor module of the apparatus forreceiving broadcast signals.

The above-described blocks may be omitted or replaced by blocks havingsimilar r identical functions according to design.

FIG. 14 illustrates a coding & modulation module according to anotherembodiment of the present invention.

The coding & modulation module shown in FIG. 14 corresponds to anotherembodiment of the coding & modulation module illustrated in FIGS. 1 to5.

To control QoS for each service or service component transmitted througheach data pipe, as described above with reference to FIG. 5, the coding& modulation module shown in FIG. 14 can include a first block 14000 forSISO, a second block 14100 for MISO, a third block 14200 for MIMO and afourth block 14300 for processing the PLS-pre/PLS-post information. Inaddition, the coding & modulation module can include blocks forprocessing data pipes equally or differently according to the design.The first to fourth blocks 14000 to 14300 shown in FIG. 14 are similarto the first to fourth blocks 5000 to 5300 illustrated in FIG. 5.

However, the first to fourth blocks 14000 to 14300 shown in FIG. 14 aredistinguished from the first to fourth blocks 5000 to 5300 illustratedin FIG. 5 in that a constellation mapper 14010 included in the first tofourth blocks 14000 to 14300 has a function different from the first tofourth blocks 5000 to 5300 illustrated in FIG. 5, a rotation & I/Qinterleaver block 14020 is present between the cell interleaver and thetime interleaver of the first to fourth blocks 14000 to 14300illustrated in FIG. 14 and the third block 14200 for MIMO has aconfiguration different from the third block 5200 for MIMO illustratedin FIG. 5. The following description focuses on these differencesbetween the first to fourth blocks 14000 to 14300 shown in FIG. 14 andthe first to fourth blocks 5000 to 5300 illustrated in FIG. 5.

The constellation mapper block 14010 shown in FIG. 14 can map an inputbit word to a complex symbol. However, the constellation mapper block14010 may not perform constellation rotation, differently from theconstellation mapper block shown in FIG. 5. The constellation mapperblock 14010 shown in FIG. 14 is commonly applicable to the first, secondand third blocks 14000, 14100 and 14200, as described above.

The rotation & I/Q interleaver block 14020 can independently interleavein-phase and quadrature-phase components of each complex symbol ofcell-interleaved data output from the cell interleaver and output thein-phase and quadrature-phase components on a symbol-by-symbol basis.The number of number of input data pieces and output data pieces of therotation & I/Q interleaver block 14020 is two or more which can bechanged by the designer. In addition, the rotation & I/Q interleaverblock 14020 may not interleave the in-phase component.

The rotation & I/Q interleaver block 14020 is commonly applicable to thefirst to fourth blocks 14000 to 14300, as described above. In this case,whether or not the rotation & I/Q interleaver block 14020 is applied tothe fourth block 14300 for processing the PLS-pre/post information canbe signaled through the above-described preamble.

The third block 14200 for MIMO can include a Q-block interleaver block14210 and a complex symbol generator block 14220, as illustrated in FIG.14.

The Q-block interleaver block 14210 can permute a parity part of anFEC-encoded FEC block received from the FEC encoder. Accordingly, aparity part of an LDPC H matrix can be made into a cyclic structure likean information part. The Q-block interleaver block 14210 can permute theorder of output bit blocks having Q size of the LDPC H matrix and thenperform row-column block interleaving to generate final bit streams.

The complex symbol generator block 14220 receives the bit streams outputfrom the Q-block interleaver block 14210, maps the bit streams tocomplex symbols and outputs the complex symbols. In this case, thecomplex symbol generator block 14220 can output the complex symbolsthrough at least two paths. This can be modified by the designer.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions according to design.

The coding & modulation module according to another embodiment of thepresent invention, illustrated in FIG. 14, can output data pipes,PLS-pre information and PLS-post information processed for respectivepaths to the frame structure module.

FIG. 15 illustrates a demapping & decoding module according to anotherembodiment of the present invention.

The demapping & decoding module shown in FIG. 15 corresponds to anotherembodiment of the demapping & decoding module illustrated in FIG. 11.The demapping & decoding module shown in FIG. 15 can perform a reverseoperation of the operation of the coding & modulation module illustratedin FIG. 14.

As shown in FIG. 15, the demapping & decoding module according toanother embodiment of the present invention can include a first block15000 for SISO, a second block 11100 for MISO, a third block 15200 forMIMO and a fourth block 14300 for processing the PLS-pre/PLS-postinformation. In addition, the demapping & decoding module can includeblocks for processing data pipes equally or differently according todesign. The first to fourth blocks 15000 to 15300 shown in FIG. 15 aresimilar to the first to fourth blocks 11000 to 11300 illustrated in FIG.11.

However, the first to fourth blocks 15000 to 15300 shown in FIG. 15 aredistinguished from the first to fourth blocks 11000 to 11300 illustratedin FIG. 11 in that an I/Q deinterleaver and derotation block 15010 ispresent between the time interleaver and the cell deinterleaver of thefirst to fourth blocks 15000 to 15300, a constellation mapper 15010included in the first to fourth blocks 15000 to 15300 has a functiondifferent from the first to fourth blocks 11000 to 11300 illustrated inFIG. 11 and the third block 15200 for MIMO has a configuration differentfrom the third block 11200 for MIMO illustrated in FIG. 11. Thefollowing description focuses on these differences between the first tofourth blocks 15000 to 15300 shown in FIG. 15 and the first to fourthblocks 11000 to 11300 illustrated in FIG. 11.

The I/Q deinterleaver & derotation block 15010 can perform a reverseprocess of the process performed by the rotation & I/Q interleaver block14020 illustrated in FIG. 14. That is, the I/Q deinterleaver &derotation block 15010 can deinterleave I and Q componentsI/Q-interleaved and transmitted by the apparatus for transmittingbroadcast signals and derotate complex symbols having the restored I andQ components.

The I/Q deinterleaver & derotation block 15010 is commonly applicable tothe first to fourth blocks 15000 to 15300, as described above. In thiscase, whether or not the I/Q deinterleaver & derotation block 15010 isapplied to the fourth block 15300 for processing the PLS-pre/postinformation can be signaled through the above-described preamble.

The constellation demapper block 15020 can perform a reverse process ofthe process performed by the constellation mapper block 14010illustrated in FIG. 14. That is, the constellation demapper block 15020can demap cell-deinterleaved data without performing derotation.

The third block 15200 for MIMO can include a complex symbol parsingblock 15210 and a Q-block deinterleaver block 15220, as shown in FIG.15.

The complex symbol parsing block 15210 can perform a reverse process ofthe process performed by the complex symbol generator block 14220illustrated in FIG. 14. That is, the complex symbol parsing block 15210can parse complex data symbols and demap the same to bit data. In thiscase, the complex symbol parsing block 15210 can receive complex datasymbols through at least two paths.

The Q-block deinterleaver block 15220 can perform a reverse process ofthe process carried out by the Q-block interleaver block 14210illustrated in FIG. 14. That is, the Q-block deinterleaver block 15220can restore Q size blocks according to row-column deinterleaving,restore the order of permuted blocks to the original order and thenrestore positions of parity bits to original positions according toparity deinterleaving.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions according to design.

As illustrated in FIG. 15, the demapping & decoding module according toanother embodiment of the present invention can output data pipes andPLS information processed for respective paths to the output processor.

As described above, the apparatus and method for transmitting broadcastsignals according to an embodiment of the present invention canmultiplex signals of different broadcast transmission/reception systemswithin the same RF channel and transmit the multiplexed signals and theapparatus and method for receiving broadcast signals according to anembodiment of the present invention can process the signals in responseto the broadcast signal transmission operation. Accordingly, it ispossible to provide a flexible broadcast transmission and receptionsystem.

A conventional broadcast signal transmitting apparatus uses a mode toperform transmission while deleting the sync byte of the TS header toinput the TS packets (or data pacekts) in the input streams as a BBframe such that the 4 byte header can be transmitted as the 3 byteheader. Alternatively, the conventional broadcast signal transmittingapparatus uses a mode to compress a PID since, in a case in which onlythe TS packet of one PID is transmitted to one DP, the PID iscontinuously transmitted. In the mode to compress the PID, one byte iscompressed and the same PID and TP value are always input to theBB-frame heater, whereby improving compression efficiency. In a case inwhich the sync byte is deleted, however, a compression rate is low. Inaddition, the mode to compress the PID has a disadvantage in that thePID must be the same.

Hereinafter, a header compression mode according to an embodiment of thepresent invention will be described.

A broadcast signal transmitting apparatus according to an embodiment ofthe present invention may perform header compression to improvetransmission efficiency for both TS and IP input streams. Because thereceiver can have a priori information on certain parts of the header,this known information can be deleted in the transmitter.

For Transport Stream, the receiver has a-priori information about thesync-byte configuration and the packet length. If the input TS streamcarries content that has only one PID, i.e., for only one servicecomponent (video, audio, etc.) or service sub-component (SVC base layer,SVC enhancement layer, MVC base view or MVC dependent views), TS packetheader compression can be applied to the Transport Stream. Also, if theinput TS carries content that has only one PMT (Program Map Table) andmultiple video and audio PIDs in one PLP, TS packet header compressioncan be applied to it as well.

The header compression mode according to the embodiment of the presentinvention may include a Sync byte deletion mode to delete only the Syncbyte, a PID compression mode to compress the PID for the same service,and a PID deletion mode to delete the PID.

FIG. 16 is a view showing a header compression block according to anembodiment of the present invention.

The upper end of FIG. 16 shows another embodiment of the mode adaptationmodule of the input formatting module according to the present inventiondescribed with reference to FIG. 3 and the lower end of FIG. 16 is aview showing detailed blocks included in the header compression block16000 included in the mode adaptation module.

As described above, the mode adaptation module of the input formattingmodule to process the multiple input streams may independently processthe respective input streams.

As shown in FIG. 16, the mode adaptation module to respectively processthe multiple input streams may include a pre-processing block(Splitter), an input interface block, an input stream synchronizerblock, a compensating delay block, a header compression block, a nulldata reuse block, a null packet deletion block, and a BB headerinsertion block. The input interface block, the input streamsynchronizer block, the compensating delay block, the null packetdeletion block, and the BB header insertion block are identical to thosedescribed with reference to FIG. 3 and, therefore, a detaileddescription thereof will be omitted.

The pre-processing block may split the input TS, IP, GS streams intomultiple service or service component (audio, video, etc.) streams.

The header compression block 16000 shown in the lower end of FIG. 16shows an operation of performing header compression with respect to theTS input stream. Specifically, the header compression block 16000according to the embodiment of the present invention may compress the TSpacket header corresponding to 4 byte out of 188 byte when receiving theTS input stream and may compress the PID while deleting the Sync byteaccording to a compression mode.

The header compression block 16000 according to the embodiment of thepresent invention may include a Sync byte deletion 16100, a PMT parser16200, a PID compression 16300, a PID converter 16400, and a TS headerreplacement 16500.

The header compression block 16000 according to the embodiment of thepresent invention may differently process the input signal according tothe header compression mode. As previously described, the headercompression mode according to the embodiment of the present inventionmay include a Sync byte deletion mode to delete only the Sync byte, aPID compression mode to compress the PID for the same service, and a PIDdeletion mode to delete the PID. Hereinafter, operations of the blocksincluded in the header compression block 16000 based on the respectivemodes will be described.

1) In the Sync byte deletion mode, the Sync byte deletion 16100 maydelete the Sync byte from the input signal and the TS header replacement16500 may transmit the compressed TS header.

2) The PID compression mode is a mode to process the TS streams havingthe same service. That is, TS stream has one PMT packet PID value andone or multiple service packet(s) with differing PID(s). In this case,the Sync byte deletion 16100 may delete the Sync byte from the inputsignal, the PMT parser 16200 may parse the PMT section describing thePID of the same service from the data output from the Sync byte deletion16100 to analyze the respective elementary PIDs. Subsequently, the PIDconverter 16400 may convert the PID into PID-SUB (or sub PID) usinginformation output from the PMT parser 16200. PID-sub is an index ofelementary PID at PMT syntax & section. Subsequently, the PIDcompression 16300 may compress the PID using the PID-Sub information andthe TS header replacement 16500 may transmit the compressed TS header.

3) The PID deletion mode should be applied to a single TS packet streamthat has only one PID. In this case, the Sync byte deletion 16100 maydelete the Sync byte and the PID compression 16300 may transmit commonPID information to the BB-frame header insertion block and delete thePID. Subsequently, the TS header replacement 16500 may transmit thecompressed TS header.

FIG. 17 is a view showing a header de-compression block according to anembodiment of the present invention.

The upper end of FIG. 17 shows another embodiment of the outputprocessor according to the present invention described with reference toFIG. 13 and the lower end of FIG. 17 is a view showing detailed blocksincluded in the header de-compression block 17000 included in the outputprocessor.

The output processor shown in FIG. 17 may perform the reverse process ofthe mode adaptation module described with reference to FIG. 16.

As shown in FIG. 17, the output processor according to the embodiment ofthe present invention may include a BB frame header parser block, a nullpacket insertion block, a null data regenerator block, a headerde-compression block, a de-jitter buffer block, a TS clock regenerationblock, and a TS recombining bloc. Operations of the respective blockscorrespond to the reverse processes of the blocks shown in FIG. 16 and,therefore, a detailed description thereof will be omitted.

The header de-compression block 17000 shown in the lower end of FIG. 17may perform the reverse process of the header compression block 16000 asdescribed above.

As shown in FIG. 17, the header de-compression block 17000 may include amode demux 17100, a PMT parser 17200, a PID convertor 17300, a PIDregenerator 17400, a TS header regenerator 17500, and a sync byteinsertion 17600.

In the same manner as in the header compression block 16000 as describedabove, the header de-compression block 17000 may differently perform theprocess according to the Header compression mode applied to thetransmission end. The header compression mode according to theembodiment of the present invention may include a Sync byte deletionmode to delete only the Sync byte, a PID compression mode to compressthe PID for the same service, and a PID deletion mode to delete the PID.Hereinafter, operations of the blocks included in the headerde-compression block 17000 based on the respective modes will bedescribed.

1) In the Sync byte deletion mode, the sync byte insertion 17600 mayrestore the Sync byte according to the header compression modeinformation output from the mode demux 17100.

2) In the PID compression mode, the PMT parser 17200 may receive the PMTaccording to the header compression mode information output from themode demux 17100 and transmit an elementary PID value included in thePMT to the PID convertor 17300. The PID convertor 17300 may restore thecompressed PID using the same. The PID regenerator 17400 may restore thePID values of data and the section packet using the received PID-SUBvalue. The TS header regenerator 17500 may restore the remaining TSheader, such as the Continuous Counter value and EI, using suchinformation. The sync byte insertion 17600 may restore the Sync byte.

3) In the PID deletion mode, the PID regenerator 17400 may restore thePID using the PID information of the BB-frame acquired by the PIDconvertor 17300, the TS header regenerator 17500 may restore theremaining TS header, such as the Continuous Counter value and EI, andthe sync byte insertion 17600 may restore the Sync byte.

FIG. 18 is a flowchart showing a header compression process according toan embodiment of the present invention.

As previously described, the header compression mode according to theembodiment of the present invention may include a Sync byte deletionmode to delete only the Sync byte, a PID compression mode to compressthe PID for the same service, and a PID deletion mode to delete the PID.The header compression mode according to the embodiment of the presentinvention may be transmitted through signaling information (mode field)having a size of 2 bits and may indicate each mode according to each bitvalue.

As shown in FIG. 18, the header compression mode according to theembodiment of the present invention may be divided into a Non-PIDcompression mode and a PID compression mode (S18000). The Non-PIDcompression mode may include a header non-compression mode and a Syncbyte deletion mode. The PID compression mode may include a PIDcompression mode to compress the PID and a PID deletion mode to deletethe PID.

In addition, the Non-PID compression mode according to the embodiment ofthe present invention may include a case in which the signalinginformation having a size of 2 bits is 00 and 01 (S18100). In addition,the PID compression mode according to the embodiment of the presentinvention may include a case in which the signaling information having asize of 2 bits is 10 and 11 (S18200).

In the Non-PID compression mode and the header non-compression mode, theheader compression block according to the embodiment of the presentinvention does not compress the header. In this case, the mode field hasa value of 00 and a header having a size of 4 bytes may be transmitted(S18110).

In the Non-PID compression mode and the Sync byte deletion mode, theheader compression block according to the embodiment of the presentinvention may perform the Sync byte deletion (S18120). In this case, themode field has a value of 01 and a header having a size of 3 bytes maybe transmitted (S18121).

In the PID compression mode and the PID compression mode to compress thePID, the header compression block according to the embodiment of thepresent invention may perform the Sync byte deletion (S18210) andperform PID compression (S18211). In this case, the mode field has avalue of 10 and a header having a size of 2 bytes and PMT_PID may betransmitted (S18212).

In the PID compression mode and the PID deletion mode, the headercompression block according to the embodiment of the present inventionmay perform the Sync byte deletion (S18220) and perform PID deletion(S18221). In this case, the mode field has a value of 11 and a headerhaving a size of 1 bytes and PID may be transmitted (S18222).

FIG. 19 is a flowchart showing a header de-compression process accordingto an embodiment of the present invention.

As previously described, the header de-compression process according tothe embodiment of the present invention corresponds to the reverseprocess of the header compression as described above. A broadcast signalreceiver according to an embodiment of the present invention may performheader de-compression using information regarding the header compressionmode processed by the transmission end. As previously described, theheader compression mode according to the embodiment of the presentinvention may be transmitted through signaling information (mode field)having a size of 2 bits and may indicate each mode according to each bitvalue. The broadcast signal receiver according to the embodiment of thepresent invention may perform header de-compression according to thereceived header de-compression mode information.

As shown in FIG. 19, the header compression mode according to theembodiment of the present invention may be divided into a Non-PIDcompression mode and a PID compression mode (S19000). The Non-PIDcompression mode may include a header non-compression mode and a Syncbyte deletion mode. The PID compression mode may include a PIDcompression mode to compress the PID and a PID deletion mode to deletethe PID.

In addition, the Non-PID compression mode according to the embodiment ofthe present invention may include a case in which the signalinginformation having a size of 2 bits is 00 and 01 (S19100). In addition,the PID compression mode according to the embodiment of the presentinvention may include a case in which the signaling information having asize of 2 bits is 10 and 11 (S19200).

In the Non-PID compression mode and the header non-compression mode, theheader de-compression block according to the embodiment of the presentinvention does not perform header de-compression.

In the Non-PID compression mode and the Sync byte deletion mode, theheader de-compression block according to the embodiment of the presentinvention may perform the sync byte insertion as the reverse process ofthe Sync byte deletion processed by the transmission end (S19110).

In the PID compression mode and the PID compression mode to compress thePID, the header de-compression block according to the embodiment of thepresent invention may perform the sync byte insertion as the reverseprocess of the Sync byte deletion (S19210) and perform the PIDde-compression as the reverse process of the PID compression (S19211).Subsequently, the header de-compression block according to theembodiment of the present invention may perform TS header regeneration(S19230).

In the PID compression mode and the PID deletion mode, the headerde-compression block according to the embodiment of the presentinvention may perform the sync byte insertion as the reverse process ofthe Sync byte deletion (S19220) and perform the PID insertion as thereverse process of the PID deletion (S19221). Subsequently, the headerde-compression block according to the embodiment of the presentinvention may perform TS header regeneration (S19230).

FIG. 20 is a view showing a relationship between a TS header compressedaccording to a Sync byte deletion mode according to an embodiment of thepresent invention and an original TS header.

FIG. 20(a) shows a raw TS header (original TS header) and FIG. 20(b)shows a TS header compressed according to a Sync byte deletion modeaccording to an embodiment of the present invention.

As shown in FIG. 20(a), the original TS header may include a sync byteof a byte, an EI (Transport error indicator) of 1 bit, an SI (Payloadunit start indicator) of 1 bit, TP (Transport priority) of 1 bit, PID of13 bits, SC (Scrambling control) of 2 bits, AFC (Adaptation fieldcontrol) of 2 bits, and CC (Continuity Counter) of 4 bits.

As shown in FIG. 20(b), the compressed TS header does not include a syncbyte. In the Sync byte deletion mode, the Sync byte (0x47) is deletedand not transmitted. The EI bit is replaced with the NI (null packetindicator) bit. The NI bit corresponds to a bit to extend a DNP value,which will hereinafter be described. Therefore, one byte can be deletedfrom the transmitted signal in this mode. A detailed description thereofwill hereinafter be given.

FIG. 21 is a view showing a relationship between a TS header compressedaccording to a PID compression mode according to an embodiment of thepresent invention and an original TS header.

FIG. 21(a) shows a raw TS header, FIG. 21(b) shows a first embodiment ofa TS header compressed according to a PID compression mode according toan embodiment of the present invention, and FIG. 21(c) shows a secondembodiment of the TS header compressed according to the PID compressionmode according to the embodiment of the present invention.

FIG. 21(a) is identical to FIG. 20(a) and, therefore, a detaileddescription thereof will be omitted.

As shown in FIGS. 21(b) and 21(c), in the PID compression mode, theheader compression block according to the embodiment of the presentinvention may delete the Sync byte and the EI from the raw TS header.The EI is an indicator indicating whether the TS packet has an error. Anenvironment having no error is premised. Consequently, the headercompression block according to the embodiment of the present inventionmay delete the EI. In this case, a broadcast signal receiving apparatusaccording to an embodiment of the present invention may perform errorchecking after decoding and re-input the EI in consideration of presenceor absence of an error.

In addition, the broadcast signal receiving apparatus according to theembodiment of the present invention may divide the PID of 13 bits intoPID-PMT and PID-SUB and transmit only the PID-SUB through the TS header.Since the PID-SUB has a length of 5 bits, a total of 8 bits of the PIDmay be compressed. The length of the PID-SUB may be changed according tointention of a designer.

The first embodiment and the second embodiment of the TS headercompressed according to the PID compression mode shown in FIGS. 21(b)and 21(c) are different from each other in terms of whether CC iscompressed and whether NI is extended. In the first embodiment shown inFIG. 21(b), the NI may have a size of 1 bit and the CC may betransmitted without compression. In this case, the CC may be used in theTS packet recombination or error estimation.

In the second embodiment shown in FIG. 21(c), the NI may have a size of4 bits and the CC may be transmitted while being compressed to 1 bit.Alternately, a CC sync flag of 1 bit may be transmitted instead of theCC. In addition, positions of the SC and the AFC may be changed. Sincethe extended NI can be used as an MSB of a DNP, which will hereinafterbe described, it is possible to display a larger number of Null packets.In this case, the position of the NI may be changed according tointention of a designer.

FIG. 22 is a table showing a PID-sub according to an embodiment of thepresent invention.

Specifically, FIG. 22(a) is a table showing a configuration mode of thePID-sub and FIG. 22(b) is a table showing sections in a case in which aPID-sub [4] value is 0.

As shown in FIG. 22(a), the PID-sub [4] value may indicate sectioninformation and PID index of the PMT.

Specifically, in a case in which the PID-sub [4] value is 0, it meansthat a PID-sub [3] value to a PID-sub [0] value indicate PIDs of theSection pocket. In this case, a total number of 16 PIDs may beindicated. In a case in which the PID-sub [4] value is 1, it means adata transmission mode. In a case in which the PID-sub [3] value is 0,it means that the PID-sub [2] value to the PID-sub [0] value indicatePID index values of the PMT. In this case, a total number of 8 PID indexvalues may be indicated. In a case in which the PID-sub [4] value is 1and the PID-sub [3] value is 1, it means a reserved region to transmitinformation extended afterwards.

FIG. 22(b) is a table showing detailed table information correspondingto each value in a case in which the PID-sub [4] value is 0.

The field values shown in FIGS. 22(a) and 22(b) or correspondinginformation may be changed according to intention of a designer.

FIG. 23 is a view showing a PID compression process according to anembodiment of the present invention.

FIG. 23(a) shows an original TS stream, FIG. 23(b) shows a TS streamafter TS compression, FIG. 23(c) is a table showing PIDs and indexes ofcomponents included in the original TS stream, and FIG. 23(d) shows aconfiguration mode of the PID-sub.

As shown in FIG. 23, the TS stream may include one video stream and twoaudio streams.

The broadcast signal transmitting apparatus according to the embodimentof the present invention may indicate sections, such as a PAT (ProgramAssociation Table) and a CAT (Conditional Access Table), using a 5 bitPID-SUB instead of a conventional 13 bit PID.

That is, since it is a case to indicate section information as describedwith reference to FIG. 22, the PID-sub [4] value becomes 0 and the PATmay be expressed as a value of 0x00 and the CAT may be expressed as avalue of 0x01 according to the table of FIG. 23(d). In addition, for thevideo stream and the audio streams, the broadcast signal transmittingapparatus according to the embodiment of the present invention maytransmit the PID information of the PMT through the BB-Frame header andcompress elementary PIDs of the remaining components using indexes andthen transmit the compressed elementary PIDs to the PID-SUB. That is, ina case indicating the PID of the components, PID-SUB [4:3] may have avalue of 10, and the remaining PID-SUB [2:0] may have a value of 001 to011 based on the PMT table. In addition, the broadcast signaltransmitting apparatus according to the embodiment of the presentinvention may set and compress the PID-SUB [2:0] to 0000.

FIG. 24 is a view showing a relationship between a TS header compressedaccording to a PID deletion mode according to an embodiment of thepresent invention and an original TS header.

FIG. 24(a) shows a raw TS header and FIG. 24(b) shows a TS headercompressed according to a PID deletion mode according to an embodimentof the present invention.

The PID deletion mode should be applied to a single TS packet streamthat has only one PID. In the PID deletion mode, the 13-bit PID isremoved from the TS packet header. As in the PID compression mode, theSync byte (0x47) is deleted and the EI bit is replaced with the NI bitat the transmitter. The 4-bit continuity counter is also reduced to 1bit. The removed 13-bit PID value is delivered in the signal frame.

FIG. 25 is a view showing a PMT according to an embodiment of thepresent invention.

The PMT according to the embodiment of the present invention may includea table_id, a section_syntax_indicator, a section length field, aprogram_number field, a version_number field, a current_next_indicator,a section_number, a last_section_number, a PCR_PID, aprogram_info_length, a first for loop for a descriptor, a second forloop having a stream_type field, an elementary_PID, an ES_info_lengthfield and a CRC 32.

The table_id is an 8-bit unsigned integer field and indicates the typeof table.

The section_syntax_indicator indicates the format of the table sectionto follow.

The section length field is a 12-bit field that gives the length of thetable section beyond this field.

The program_number field is a 16-bit unsigned integer that uniquelyidentifies each program service present in a transport stream.

The version_number field is a 5-bit unsigned integer field and indicatesthe version number of the table.

The current_next_indicator indicates if data is current in effect or isfor future use.

The section_number is an index indicating which table this is in arelated sequence of tables.

The last_section_number indicates which table is the last table in thesequence of tables.

The PCR_PID is a packet identifier that contains the program clockreference used to improve the random access accuracy of the stream'stiming that is derived from the program timestamp.

The program_info_length field indicates a number of bytes that followfor the program descriptors.

The first for loop for a descriptor denotes the location of a descriptorloop that may contain zero or more individual descriptors.

The stream type field in the second for loop defines the structure ofthe data contained within the elementary packet identifier.

The elementary_PID in the second for loop is a packet identifier thatcontains the stream type data.

The ES_info_length field in the second for loop indicates a number ofbytes that follow for the elementary stream descriptors.

The CRC 32 is a checksum of the entire table excluding the pointerfield, pointer filler bytes and the trailing CRC32.

FIG. 26 is a view showing a relationship between a TS header compressedaccording to a PID compression mode according to another embodiment ofthe present invention and an original TS header.

FIG. 26(a) shows an original TS header and FIG. 26(b) shows a TS headercompressed according to a PID compression mode according to anotherembodiment of the present invention.

The compressed TS header shown in FIG. 26 is different from thecompressed TS header shown in FIG. 21 in that DNP_(MSB) bit is inputinstead of the deleted EI bit and that the 13 bit PID is compressed intoan 8 bit sub-PID.

The PID compression mode should be applied when a single DP contains oneTS packet stream that has one PMT packet PID value and one or multipleservice packet(s) with differing PID(s). In this case, the 13-bit PIDvalue can be compressed to an 8-bit sub-PID. The MSB of the 8-bitsub-PID indicates which type of packet is delivered. The following 7bits indicate the address for delivering packets. FIG. 26 shows therelationship between the original PID and sub-PID. According to the PIDcompression mode according to another embodiment of the presentinvention, the Sync byte (0x47) is deleted and the TS error indicatorbit is replaced with the DNP_(MSB) bit. The 4-bit continuity counter canbe reduced to 1 bit (continuity counter sync flag), which providessynchronization of the receiver's 4-bit counter.

FIG. 27 is a view showing a table indicating a PID-sub according toanother embodiment of the present invention and a mapping table forcontinuity counter compression.

Specifically, FIG. 27(a) is a table showing a configuration mode of thePID-sub (or sub-PID) and FIG. 27(b) is a mapping table for continuitycounter compression.

As shown in FIG. 27(a), in a case in which sub-PID [7] value is 0, theremaining sub-PID [6:0] values may indicate predetermined PIDs.Specifically, specific values of the sub-PID [6:0] may indicate PIDs forthe section packets, such as the PAT and the CAT, or null packets. In acase in which sub-PID [7] value is 1, the remaining sub-PID [6:0] valuesmay indicate indexes of PID values of data or components. Actually, thePID values may be transmitted through signaling information, i.e. PLSinformation, in a signal frame.

FIG. 27(b) is a mapping table for continuity counter compression. Onlyin a case in which a value of a continuity counter is 0000, a value of acontinuity counter sync flag may be set to 1. For the remaining values,a value of the continuity counter sync flag may be set to 0.

The field values shown in FIGS. 27(a) and 27(b) or correspondinginformation may be changed according to intention of a designer.

FIG. 28 is a view showing a PID compression process according to anotherembodiment of the present invention.

FIG. 28(a) shows an original TS stream and FIG. 28(b) shows a TS streamafter TS compression.

As shown in FIG. 28(a), the original TS packet or TS stream may includevarious PIDs. In a case in which the included packets are sectionpackets (CAT:0x001, PAT:0x000, etc.) or Null packets (0x1FF), thesub-PID [7] value may be set to 0 as previously described, the PID ofthe PAT may be set to 0x00, the PID of the CAT may be set to 0x01, andthe PID of the Null packet may be set to 0x1F.

For data or components, the PIDs may be set to 0x010, 0x011, and 0x014.These values may be transmitted through the PLS, the sub-PID [7] valuemay be set to 1, and the sub-PID [6:0] may transmit only the indexesstored in the PLS.

In response thereto, the broadcast signal receiving apparatus accordingto the embodiment of the present invention may restore the PIDs usingthe index values shown in the above table and the real PID valuestransmitted through the PLS.

When receiving a TS stream as input data, the conventional broadcastsignal transmitting apparatus divides the TS stream into service orserver component unit packets for efficient transmission. In thisprocess, packets other than the service or server component unit packetsmay be replaced with null packets. Since the null packets have noinformation although the null packets are need for CBR (Constant BitRate) transmission, the null packets may be deleted during transmission,thereby improving transmission efficiency. In this case, the broadcastsignal transmitting apparatus may insert a DNP counter (or DNP)indicating the number of the deleted null packets into a start part ofeach TS packet to restore the null packets deleted at the receiving end.The DNP counter has a size of 8 bits. The DNP counter may besequentially increased by 1 according to the number of the deleted nullpackets to a value of maximum 255. In a future broadcast serviceaccording to an embodiment of the present invention, however, a signalhaving a low data rate may be transmitted, several services may be splitinto small units, or a large image signal, such as UD, may be split. Forthis reason, a larger number of continuous null packets than aconventional broadcast service may be present. When DNP reaches themaximum allowed value of the DNP counter, and if the following packet isagain a null-packet, then this null-packet is kept as a useful packetand transmitted.

In this case, however, the null packets may be inserted with the resultthat transmission efficiency of the TS stream may be lowered. In orderto solve this problem, the DNP may be extended to 2 bytes. In thismethod, however, transmission efficiency of the TS stream may also belowered.

Hereinafter, a DNP extension method to solve the above problem will bedescribed. Specifically, the present invention proposes a method oftransmitting DNPE (DNP Extension) while being contained in a compressedTS header as the DNP extension method. A detailed description willhereinafter be given.

In the receiver, removed null packets can be re-inserted in the exactplace where they were originally by reference to a DNP counter that isinserted in the transmission, thus guaranteeing constant bit-rate andavoiding the need for time-stamp (PCR) updating.

FIG. 29 is a view showing a null packet deletion block according toanother embodiment of the present invention.

The null packet deletion block 29000 shown in FIG. 29 is different fromthe null packet deletion block 3300 described with reference to FIG. 3.

The Null-packet Deletion block is used only for the TS input streamcase. Some TS input streams or split TS streams may have a large numberof null-packets present in order to accommodate VBR (variable bit-rate)services in a CBR TS stream.

The null packet deletion block 29000 according to the embodiment of thepresent invention may include a Null packet check block 29100, a nullpacket deletion block 29200, a DNP insertion block 29300, and a Nullpacket counter block 29400. Hereinafter, operations of the respectiveblocks will be described.

The Null packet check block 29100 may check whether the current packetis a null packet through the PID of the input TS packet.

Upon checking that the current packet is the null packet, the nullpacket deletion block 29200 may delete the corresponding null packet. Inthis case, the DNP insertion block 29300 may count the number of thedeleted null packet and insert a DNP (deleted null-packet) counterbefore the TS packet.

Upon checking that the current packet is not the null packet, the nullpacket deletion block 29200 does not perform any action with respect tothe corresponding null packet and the Null packet counter block 29400may reset the number of the null packets to 0. Subsequently, the DNPinsertion block 29300 may insert a DNP before the TS packet using theNull packet counter value calculated by the Null packet counter block29400. Then, DNP insertion block 29300 may insert NDP in front of thenext TS packet by using Null packet counter calculated in

In a case in which a DNP offset mode is used, the Null packet counterblock 29400 may extract an offset of the DNP value by a BB-Frame sectionand insert the DNP offset value into a BB-Frame header. In this case,the DNP insertion block 29300 may insert a compressed DNP value beforethe TS packet. The DNP offset mode will hereinafter be described indetail.

FIG. 30 is a view showing a null packet insertion block according toanother embodiment of the present invention.

The null packet insertion block 30000 shown in FIG. 30 is different fromthe null packet deletion block 13100 described with reference to FIG.13.

The null packet insertion block 30000 according to the embodiment of thepresent invention may include a DNP check block 30100, a null packetinsertion block 30200, and a null packet generator block 30300.Hereinafter, operations of the respective blocks will be described.

The DNP check block 30100 may extract a DNP value and a DNP offset valuefrom input data. Subsequently, the null packet insertion block 30200 mayreceive and insert a Null packet pre-generated by the null packetgenerator block 30300.

FIG. 31 is a view showing a DNP extension method according to anembodiment of the present invention.

FIG. 31(a) shows a DNP extension method of inserting a 1 bit or 4 bitDNPE into a TS header compressed according to a PID compression modeaccording to an embodiment of the present invention.

FIG. 31(b) shows a DNP extension method of inserting a 1 bit DNPE into aTS header compressed according to a PID deletion mode according to anembodiment of the present invention.

When Null-packet Deletion is used, after transmission of a data TSpacket, a counter is first reset and then incremented at each deletednull-packet. The counter value, designated DNP, indicates the number ofdeleted null-packets. A DNP according to an embodiment of the presentinvention may count a maximum of 255 continuous null packets. A DNPEaccording to an embodiment of the present invention is used to extendthe maximum value of the above DNP. The DNPE may be used when the numberof the continuous null packets exceeds 255.

The DNP according to an embodiment of the present invention may beinserted in front of the next data TS packet, and the DNPE according toan embodiment of the present invention may be embedded in the compressedTS packet header of the next data TS packet.

For a compressed TS packet header shown at the upper end of FIG. 31(a),a 1 bit DNPE is used and, therefore, the maximum value of the DNPbecomes 9 bits, which is obtained by adding 1 bit to the existing 8bits. Consequently, the DNP counter may indicate a total of 511 deletednull packets. For a compressed TS packet header shown at the lower endof FIG. 31(a), a 4 bit DNPE is used and, therefore, the maximum value ofthe DNP becomes 12 bits, which is obtained by adding 4 bits to theexisting 8 bits. Consequently, the DNP counter may indicate a total of4095 deleted null packets.

For a compressed TS packet header shown in FIG. 31(b), a PID is deletedand a 1 bit DNPE may be inserted into the first part of the compressedTS packet header. In this case, the maximum value of the DNP becomes 9bits, which is obtained by adding 1 bit to the existing 8 bits.Consequently, the DNP counter may indicate a total of 511 deleted nullpackets.

The size and insertion position of the DNPE may be changed according tointention of a designer.

FIG. 32 is a view showing a DNP offset according to an embodiment of thepresent invention.

FIG. 32(a) shows a conventional process of splitting an input TS streamand FIG. 32(b) shows a DNP offset of audio packets.

In a case in which the input TS stream is split as shown in FIG. 32(a),a plurality of null packets may be generated. Particularly, in a case inwhich a plurality of TS streams is combined as in a Big TS stream, oneTS stream is slit into component levels, or big TS is split into a videopacket and an audio packet as in a UD service, null packets may beperiodically inserted. In this case, the number of basically insertednull packets may be preset although the number of inserted null packetsmay be changed.

TS input streams or split TS streams having consecutive TS packets anddeleted null packets may be mapped into a payload of BB frame as shownin (b). The BB frame includes a BB frame header and the payload. The BBframe header may be inserted in front of the payload.

The present invention proposes a method of transmitting the number ofbasically inserted null packets, i.e. basic values, using the DNP offsetthrough the BB frame. The DNP-offset according to the embodiment of thepresent invention is the minimum number of DNPs belonging to the sameBBF. The DNP offset can be transmitted through the BB frame header. As aresult, it is possible to reduce the number of DNPs inserted before theTS packet, to achieve efficient TS packet transmission, and to remove alarger number of null packets.

The DNP offset of the present invention may be used simultaneously withthe above DNP extension. The size, etc. of the DNP offset may be changedaccording to intention of a designer.

FIG. 33 is a flowchart illustrating a method for transmitting broadcastsignals according to an embodiment of the present invention.

The apparatus for transmitting broadcast signals according to anembodiment of the present invention can format at least one input streamto output DP (Data Pipe) data corresponding to each of a plurality ofDPs. As described above, a data pipe is a logical channel in thephysical layer that carries service data or related metadata, which maycarry one or multiple service(s) or service component(s). Data carriedon a data pipe can be referred to as DP data. Also, the apparatus fortransmitting broadcast signals according to an embodiment of the presentinvention further splits the at least one input stream into the DP datahaving data packets and compress a header in the each of the datapackets according to a header compression mode. The detail process ofstep S33000 is as described in FIGS. 16 to 32.

The apparatus for transmitting broadcast signals according to anembodiment of the present invention can encode data pipe (DP) datacorresponding to each of a plurality of DPs (S33100). The detailedprocess of step S30000 is as described in FIG. 1, 5 or 14.

The apparatus for transmitting broadcast signals according to anembodiment of the present invention can map the encoded DP data ontoconstellations (S33200). In addition, the apparatus for transmittingbroadcast signals according to an embodiment of the present inventioncan perform MIMO processing on the mapped DP data. The detailed processof this step is as described in FIG. 1, 5 or 14.

Then, the apparatus for transmitting broadcast signals according to anembodiment of the present invention can time-interleave the mapped DPdata (S33300).

Subsequently, the apparatus for transmitting broadcast signals accordingto an embodiment of the present invention can build at least on signalframe including the time-interleaved DP data (S33400). The detailedprocess of this step is as described in FIG. 1 or 6.

The apparatus for transmitting broadcast signals according to anembodiment of the present invention can modulate data included in thebuilt signal frame using an OFDM scheme (S33500). The detailed processof this step is as described in FIG. 1 or 7.

The apparatus for transmitting broadcast signals according to anembodiment of the present invention can transmit broadcast signalsincluding the signal frame (S33600). The detailed process of this stepis as described in FIG. 1 or 7.

FIG. 34 is a flowchart illustrating a method for receiving broadcastsignals according to an embodiment of the present invention.

The flowchart shown in FIG. 34 corresponds to a reverse process of thebroadcast signal transmission method according to an embodiment of thepresent invention, described with reference to FIG. 33.

The apparatus for receiving broadcast signals according to an embodimentof the present invention can receive broadcast signals (S34000) anddemodulate received broadcast signals using an OFDM scheme (S34100).Details are as described in FIG. 8 or 9.

The apparatus for receiving broadcast signals according to an embodimentof the present invention can parse at least one signal frame from thedemodulated broadcast signals (S34200). Details are as described in FIG.8 or 10. In this case, the at least one signal frame can include DP datafor carrying services or service components.

Subsequently, the apparatus for receiving broadcast signals according toan embodiment of the present invention can time-deinterleave the DP dataincluded in the parsed signal frame (S34300).

Then, the apparatus for receiving broadcast signals according to anembodiment of the present invention can demap the time-deinterleaved DPdata (S34400). Details are as described in FIG. 8 or 11 and FIG. 15.

The apparatus for receiving broadcast signals according to an embodimentof the present invention can decode the demapped DP data (S34500).Details are as described in FIG. 8 or 11 and FIG. 15.

The apparatus for receiving broadcast signals according to an embodimentof the present invention can output process the decoded DP data. Morespecifically, the apparatus for receiving broadcast signals according toan embodiment of the present invention can decompress a header in theeach of the data packets in the decoded DP data according to a headercompression mode and recombine the data packets. Details are asdescribed in FIGS. 16 to 32.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A method for transmitting broadcast signals, themethod comprising: formatting an input stream to output PLP (PhysicalLayer Pipe) data including a data packet, wherein the input streamincludes at least one null packet and input packets, wherein theformatting further includes: deleting the at least one null packet,removing a sync byte from each input packet, and selectively compressingheaders of the input packets, wherein the compressing of the headers isperformed by transmitting common information of the headers of the inputpackets once in the data packet that carries payloads of the inputpackets, and wherein a header of the data packet includes firstinformation for identifying whether the compressing of the headers isapplied and second information for identifying a number of the deletedat least one null packet; FEC (Forward Error Correction) encoding thePLP data; bit interleaving the FEC encoded PLP data; mapping the bitinterleaved PLP data onto constellations; time interleaving the mappedPLP data; building at least one signal frame including the timeinterleaved PLP data; modulating data in the built at least one signalframe by OFDM (Orthogonal Frequency Division Multiplex) scheme; andtransmitting the broadcast signals having the modulated data.
 2. Themethod of claim 1, wherein the header of the data packet furtherincludes type information for identifying a packet type of the inputpackets.
 3. A method for receiving broadcast signals, the methodcomprising: receiving the broadcast signals; demodulating the receivedbroadcast signals by OFDM (Orthogonal Frequency Division Multiplex)scheme; parsing at least one signal frame of the demodulated broadcastsignals, wherein the at least one signal frame includes PLP (PhysicalLayer Pipe) data; time deinterleaving the PLP data; de-mapping the timedeinterleaved PLP data; bit deinterleaving the de-mapped PLP data; FEC(Forward Error Correction) decoding the bit deinterleaved PLP dataincluding a data packet that carries payloads of output packets; andoutput processing the FEC decoded PLP data to output an output streamincluding the output packets, wherein the output processing furtherincludes: parsing the data packet in the FEC decoded PLP data, wherein aheader of the data packet includes first information for identifyingwhether headers of the output packets are compressed and secondinformation for identifying a number of at least one null packet to beregenerated, selectively restoring the headers of the output packetsbased on the first information, wherein the restoring of the headers isperformed based on common information of the headers of the outputpackets received once in the data packet, inserting a sync byte intoeach output packet, and regenerating the at least one null packet in theoutput stream based on the second information.
 4. The method of claim 3,wherein the header of the data packet further includes type informationfor identifying a packet type of the output packets.
 5. An apparatus fortransmitting broadcast signals, the apparatus comprising: an inputformatter that formats an input stream to output PLP (Physical LayerPipe) data including a data packet, wherein the input stream includes atleast one null packet and input packets, wherein the input formatterfurther includes: deleting the at least one null packet, removing a syncbyte from each input packet, and selectively compressing headers of theinput packets, wherein the compressing of the headers is performed bytransmitting common information of the headers of the input packets oncein the data packet that carries payloads of the input packets, andwherein a header of the data packet includes first information foridentifying whether the compressing of the headers is applied and secondinformation for identifying a number of the deleted at least one nullpacket; a FEC (Forward Error Correction) encoder that FEC encodes thePLP data; a bit interleaver that bit interleaves the FEC encoded PLPdata; a mapper that maps the bit-interleaved PLP data ontoconstellations; a time interleaver that time interleaves the mapped PLPdata; a frame builder that builds at least one signal frame includingthe time interleaved PLP data; a modulator that modulates data in thebuilt at least one signal frame by OFDM (Orthogonal Frequency DivisionMultiplex) scheme; and a transmitter that transmits the broadcastsignals having the modulated data.
 6. The apparatus of claim 5, whereinthe header of the data packet further includes type information foridentifying a packet type of the input packets.
 7. An apparatus forreceiving broadcast signals, the apparatus comprising: a receiver thatreceives the broadcast signals; a demodulator that demodulates thereceived broadcast signals by OFDM (Orthogonal Frequency DivisionMultiplex) scheme; a frame parser that parses at least one signal frameof the demodulated broadcast signals, wherein the at least one signalframe includes PLP (Physical Layer Pipe) data; a time deinterleaver thattime deinterleaves the PLP data; a de-mapper that demaps the timedeinterleaved PLP data; a bit deinterleaver that bit deinterleaves thede-mapped PLP data; a FEC (Forward Error Correction) decoder that FECdecodes the bit-deinterleaved PLP data including a data packet thatcarries payloads of output packets; and an output processor that outputprocesses the FEC decoded PLP data to output an output stream includingthe output packets, wherein the output processor further includes:parsing the data packet in the FEC decoded PLP data, wherein a header ofthe data packet includes first information for identifying whetherheaders of the output packets are compressed and second information foridentifying a number of at least one null packet to be regenerated,selectively restoring the headers of the output packets based on thefirst information, wherein the restoring of the headers is performedbased on common information of the headers of the output packetsreceived once in the data packet, inserting a sync byte into each outputpacket, and regenerating the at least one null packets in the outputstream based on the second information.
 8. The apparatus of claim 7,wherein the header of the data packet further includes type informationfor identifying a packet type of the output packets.